The advantages of loudspeakers provided with diaphragms of plastic material are already known and include their vibration response uniformity in the different zones of the diaphragm and their physical uniformity in comparison to paper diaphragms. This uniformity of the diaphragm produces a reduction in the number of resonant frequences which results in less "coloration" for the listener.
Nevertheless, plastic diaphragms which have low mechanical characteristics because of the low heat resistance of the plastic sheet material of which they are made (of the order of 100.degree.-150.degree. C. in general) limit the permissible power of the loudspeakers.